1. Field of the Invention
The invention relates to an electrophotographic image forming device, such as a laser printer, copier, facsimile machine, etc. Particularly, the invention relates to a processing cartridge for the electrophotographic image forming device.
2. Description of the Related Art
A conventional processing cartridge, as illustrated in FIG. 1, comprises a developing unit 1, a photosensitive unit 2, a first side plate 3, a second side plate 4 and a sealing plug 5. The developing unit 1 comprise at least a case 8 and a developing member 7; the photosensitive unit 2 comprise at least a photosensitive member (not indicated); the first side plate 3 and the second side plate 4 are respectively mounted on both ends of the developing unit 1 and are used to support the developing member 7. The developing unit 1 can store developer and has also a developer inlet 6, through which the developer enters and is stored in the developing unit 1. The developer inlet 6 is closed with the sealing plug 5 after the developer is stored in the developing unit 1, and then, one end of the case 8, at least including the sealing plug 5, is covered by the first side plate 3 and the other end of the case is covered by the second side plate 4. Finally, the developing unit 1 mounted with the first side plate 3, the second side plate 4 and the sealing plug 5, and the photosensitive unit 2 will be assembled together.
When the electrophotographic image forming device operates, it receives external signals for an electrostatic latent image to be formed on the photosensitive member in the photosensitive unit 2 on the processing cartridge. Afterwards, the processing cartridge receives the driving power and voltage from the electrophotographic image forming device to output the developer, as stored in the developing unit 1 on the processing cartridge, to the developing member 7, and a developer layer will be formed on the developing member 7. The developer layer develops the electrostatic latent image on the photosensitive member in the photosensitive unit 2 and then the electrophotographic image forming device transfers the developed electrostatic latent image onto a printing medium.
Some of the transferred developer will remain on the photosensitive member due to incomplete transfer and finally be cleaned down into the photosensitive unit 2 and stored in the chamber 2a as shown in FIG. 2. The chamber 2a has many ribs in it for enhancing the strength thereof.
After the processing cartridge reaches a certain point of its useful life, the photosensitive unit will be filled up with the developer cleaned down from the photosensitive member and cannot store developer any more. If the processing cartridge continues to operate, the residual developer on the photosensitive member could not be cleaned up, which therefore affects the normal operation of the processing cartridge.